High-profile restaurants run by celebrity chefs George Calombaris and Shannon Bennett have also been embroiled in underpayment scandals. Bennett denies the claims.

A 2015 report by the Fair Work Ombudsman found about half of all restaurants and cafes audited did not pay legal rates.

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And in July this year the Ombudsman reported that 81 per cent of businesses inspected in Victoria Street, Richmond, did not comply with workplace laws.

The Fair Work Ombudsman recently signed a three-year memorandum of understanding with the industry group aimed at improving compliance with workplace laws in fast food outlets, restaurants and cafes.

Ombudsman Sandra Parker said getting businesses to abide by workplace laws was a priority.

‘’Improving compliance will also establish a level playing field by eliminating the unfair competitive advantage gained by employers who are underpaying staff,’’ she said.

Ms Payne said a lot of the Ombudsman's resources and private resources had been devoted to auditing and prosecuting individual businesses, especially after media exposure.

“How do we come at this in a strategic, systemic way? How do we come at this in a strategic industry-wide manner that addresses the causes and finds solutions?”

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The comments come just days after Rockpool frontman Neil Perry told Fairfax Media he believed his group was one of ''very few, if any'' in the industry that now complied with workplace laws.

He was commenting after Rockpool made workplace changes to tackle problems revealed byFairfax mid-year, including permanent chefs working excessive, unpaid overtime – a breach of the law. Staff were being paid for 38 hours a week and working 20 to 30 hours of unpaid overtime.

That pushed their wage well below minimum award rates, equating to as little as $15 an hour.

The group’s restaurants include Sake, Rosetta, Munich Brauhaus, the Bavarian, and the flagship, Rockpool.

In Victoria, established union United Voice has launched a hospitality offshoot, Hospo Voice as part of its campaign around wages and conditions in hospitality.

United Voice secretary Jess Walsh.Credit:Ken Irwin

United Voice state secretary Jess Walsh said the Hospo Voice model was a response to what the often-transient workforce itself wanted.

Ms Walsh said there was no excuse for underpayment.

‘’I think it’s as simple as this behaviour has been allowed to go on,’’ she said. ‘’If you can’t make a good hospitality business thrive, you should think about what you're doing’’.

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The industry association has lobbied for cuts to weekend and evening penalty rates for restaurants and cafes and is now pushing for a flat wage rate across the week to recognise the seven-day nature of the industry.

It has long argued that the combination of penalty payments and the complexity of managing payroll made it difficult to run a profitable hospitality business.

Nonetheless, Ms Payne said there was no excuse for businesses flouting workplace laws. “The award is the award. It’s the law. Businesses must comply with their obligations.

“We don’t want people underpaying, because they’re competing with people who are paying properly and undercutting them.”

Ms Payne said it was possible for restaurants and cafes to be profitable and thrive, if they “do their homework and business planning”.

“Where we find people coming undone is when they go into it with all the love and passion, they love food they love coffee, they love wine … without stopping to do a business plan … What are the costs of hiring people, of putting a plate of food on the table?

“Just loving food is not going to be enough to make it a business success.”

Ben Schneiders is an investigative journalist at The Age and has reported extensively on wage theft, corruption, business, politics and the labour movement. A three-time Walkley Award winner, he has been part of The Age’s investigative unit since 2015.